internal static string GetClosestClientMediaType(this IEnumerable <TextOutputFormatter> outputFormatters, ResourceFormat resourceFormat, IEnumerable <string> acceptHeaders)
{
// When overriding the MediaType with the query string parameter
// some browsers don't display the response when returning "application/fhir+xml".
// For this reason we try to match a media type from the OutputFormatter with the request Accept header.
string closestClientMediaType = null;
string preferred = resourceFormat.ToContentType();
if (outputFormatters != null && acceptHeaders != null)
{
// Gets formatters that can write the desired format
var validFormatters = outputFormatters
.Where(x => x.GetSupportedContentTypes(preferred, typeof(Resource)) != null)
.ToArray();
var acceptHeadersArray = acceptHeaders.ToArray();
// Using the valid formatters, select the correct content type header for the client
closestClientMediaType = acceptHeadersArray
.SelectMany(x => validFormatters.SelectMany(y => y.GetSupportedContentTypes(x, typeof(Resource)) ?? Enumerable.Empty <string>()))
.Distinct()
.Intersect(acceptHeadersArray)
.FirstOrDefault();
}
return(closestClientMediaType ?? preferred);
}
public async Task CheckRequestedContentTypeAsync(HttpContext httpContext)
{
var acceptHeaders = httpContext.Request.GetTypedHeaders().Accept;
string formatOverride = GetFormatFromQueryString(httpContext);
// Check the _format first since it takes precedence over the accept header.
if (!string.IsNullOrEmpty(formatOverride))
{
ResourceFormat resourceFormat = ContentType.GetResourceFormatFromFormatParam(formatOverride);
if (!await IsFormatSupportedAsync(resourceFormat))
{
throw new NotAcceptableException(Api.Resources.UnsupportedFormatParameter);
}
string closestClientMediaType = _outputFormatters.GetClosestClientMediaType(resourceFormat.ToContentType(), acceptHeaders?.Select(x => x.MediaType.Value));
// Overrides output format type
httpContext.Response.ContentType = closestClientMediaType;
}
else
{
if (acceptHeaders != null && acceptHeaders.All(a => a.MediaType != "*/*"))
{
var isAcceptHeaderValid = false;
foreach (MediaTypeHeaderValue acceptHeader in acceptHeaders)
{
isAcceptHeaderValid = await IsFormatSupportedAsync(acceptHeader.MediaType.ToString());
if (isAcceptHeaderValid)
{
break;
}
}
if (!isAcceptHeaderValid)
{
throw new NotAcceptableException(string.Format(Api.Resources.UnsupportedHeaderValue, HeaderNames.Accept));
}
}
}
}
